Magnetic separator



Jan. 14, 1930. R. s. RILEYA ET AL 1,743,237

MAGNETIC SEPARATOR Filed March 29. 1926 3 Sheets-Sheet l ATTO NEY Jan. 14, 1930. R, s, RlLEx'( ET AL 1,743,237

MAGNETIC SEPARATOR Filed March 29. 1926 5 Sheetfs-Shet 2 NVENToRs wn-N asses j?. SANFoH Hlm HARO@ F. l/IQLTON W @Y1-M f w EY Jan. 14, 1930. R. s. RILEY ET AL 1,743,237

MAGNETIC SEPARATOR Filed March 29. 1926 3 Sheets-Sheet 3 LMMIIWWIIIMIII rglllll llllllllllll 4/ gum e 0 INVENTORS wfTN ESSES SANFORD RILEY Q i I i 1 HAROLD/f," WqLmv m Q-@TM I ATTO NEY Patented Jan. 14, 1930 UNTE STATES PATNT OFFICE ROBERT SANFORD RILEY AND HAROLD F. WALTON, OF WORCESTER, MASSACHUSETTS,

ASSGNORS TO RILEY STOKER CORPORATION, OF WORCESTER, MASSACHUSETTS,

CORPORATION OF TiIASSACI-IU SETTS MAGNETIC SEPARATOR Application filed. March 29, 1926.

This invention relates to magnetic separating and feeding apparatus and more particularly to a device which will feed material, such as coal, at a desired rate and at the same time separate therefrom the foreign iron bodies.

In order to burn pulverized fuel efficiently in a furnace, it is desirable that the coal be pulverized and fed to the burners at an adjustable rate. This method of combustion requires in particular that the coal be fed continuously since an interruption in the feeding operation causes the flame to go out. The unit system of burning pulverized fuel involves the use of a pulverizing apparatus, a device to feed the coal continuously thereto, and a blower system to transmit the fuel directly to the furnace burners. The fuel should be ground very finely, and an eiiicient type of pulverizer requires rapidly rotated impact devices capable of breaking the coal particles to a line degree of subdivision. One pulverizer suitable for this purpose comprises a number of intermeshing rows of pegs mounted on a rotatable disk and an opposed casing wall in such a manner that they may break the coal by successive impacts thereagainst. If a heavy body, such as tramp iron, which is not easily crushed by the impact pegs, should enter the pulverizer casing, it might easily cause the pegs to be broken from their settings and so necessitate shutting down the machine for repairs and put the furnace out of commission.

Various forms of electro-magnetic separators have been proposed for separating magnetic material from coal, but such devices have involved types of construction which render them inefiicient and, therefore, commercially impractical for this purpose. A magnetic separator which is useful for this purpose should require a low power consumption and the magnetic flux should be concentrated at the locality where the material is being fed. There should be the minimum of leakage of the flux to other parts of the device The magnetic material should be held securely by the magnet until it has been removed from the path of the falling stream of coal, and it should then be released easily Serial No. 98,124.

and discharged. It should not obstruct the flow of material otherwise, so that large bodies, as well as smaller particles, may pass unobstructedly over the magnet, and the magnetic separator should be so located and so associated with the parts of the feeding apparatus as to provide a type of machine which is efficient, simply constructed, easily operated and as near fool-proof as possible.

Tt is accordingly the primary object of our invention to provide a magnetic separator which will overcome the difficulties heretofore met in this art and which will separate magnetizable bodies efficiently and positively from a stream of material.

It is a further object to provide a combination feeding device and magnetic separator which is arranged to feed material at a desired rate and positively separate therefrom the magnetizable bodies which may be present without interfering with the operation of feeding.

Vith these and other objects in view as will be apparent from the following disclosure, our invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawings showing one embodiment of this invention and in which like numerals indicate like parts:

Fig. l is a vertical section on approximately the line l-l of Fig. 3;

Fig. 2 is an elevation with parts broken away showing the opposite side ofthe'device from-that illustrated in Fig. l;

Fig. 3 is a horizontal section on the line 3-3 of Fig. l;

Fig. 4 is'a vertical elevation, partly in section, of the feeding table and electro-magnetic device;

Fig. 5 is a perspective view of the casting which forms the core and pole pieces of the magnet;

Fig. 6 is a perspective view of a plate which in combination with'a part of the table forms one of the pole pieces of the magnet; and

Fi g.7 is a perspective view of the coil which constitutes the electro-magnetic circuit surrounding the central pole piece.

In accordance with one phase of our inico ` with suitable feeding apparatus arranged to present al localized stream ofmaterial thereto, and the magnet is located preferably beneath the table, the parts being so yarranged that the magnetic lines ,of lflux will pass directly from the core of the magnet to the table and material thereon. To this end we prefer to provide :the table itself with iron portions which yterm pole pieces for the magnet, and the core of .the magnet is ,arranged opposite one of these pole pieces and vin line therewith so that the axis of :the magnetic coil will pass thru the pole piece and the lines of force will pass directly thereto. This pole piece is separated by la gap from a .second pole piece so arranged that material passing over the table will ltend to bridge over this gap .and ythe particles of magnetic material in the falling stream will thus ybe held in a strong field of flux. The magnet may also comprise .a further iron portion forming a return path from the second pole piece to the coreof the magnet, and in our preferred form V.we utilize an E-.shaped :type of magnet, the central core of which is Wound with an electro-magnetic coil Yand which is so arranged that the axis of this coil will pass thru one of the pole pieces on the rotatable table.

Referring more 'particularly tothe drawings which illustrate one Aemlmdimentof this invention, the casing 10, which may form a part a pulverizing apparatus, is provided with a vertical shaft 11 suitably mounted in bearings within the casing and arranged to be rotated at one or more speeds by a suitable driving Y mechanism. A horizontal disk shaped ytable top 12 issupported on a reduced portion of the shaft 11 and keycd'thereto for rotation with Vthe shaft. A hopper 13 is mounted above the table top on the casing 1.0 and arranged to feed material thereto. The flange 141 depending from the top 115 of the casing and surrounding the hopper opening forms the vlower portion :of the hopper and extends nearly Ainto contact with the table. The hopper preferably provided with an opening 16 arranged to permit material to escape onto the annular portion 17 of the table which rlies outside of the hopper. The size of this opening is such relative to .the width of the Vannular portion 17 that the material which escapes through lthe opening will normally `lie in repose en the table. In

order to .remove material therefrom at a l'egulatable rate, a scraper 18 is adjustably mounted with its lower edge in substantial Contact with the top surface of the table, and the parts are so arranged that as the table rotates the material issuing' from within the hopper will be scraped outwardly through the opening and caused to fall over the table edge. In order to provide an extensive surface over which the material must pass after it has been removed from the hopper and give an electro-magnet sufficient opportunity to remove magnetizable bodies therefrom, the table 12 is made sloping in shape. This is preferably accomplished by providing the disk top with a depending skirt v20 shaped like the frustum of a cone. This skirt is hollow and provides space beneath it for a stationary electro-magnetic device -so arranged that it will apply a strong magnetic field to the falling stream of material. The casing 10 is provided with a later-al extension, shown at the top of F 3, having an enlarged space 22 opposite the outer end of the knife 1.8 which communicates with a lpipe 23 arranged to lead to the pulverizer or to a suitable -Storage space. The extension to the casing is provided with a floor-21l; (Fig. 2) which extends between the space 22 and an .opening 25 leading to a chute through which the foreign bodies are to be discharged. These parts form a partition separating the t-wo openings provided for the difieren-t materials. A knife 27 suitably fastened to the side of the ycasing n has an inner edge in substantial contact with the skirt and is arranged so as to sweep any material carried thereon into the opening '25. Hence, any material withdrawn by the magnet and held to the revolving skirt will be .effectively separated from the falling stream which passes to the chute 28.

Located beneath theskirtand Aopposite the opening 22 and extending approximately to the opening 25 is an electro-magnet which is constructed substantially as shown in Figs. 4, 5, 6 and 7. This comprises an iron casting 80, as shown in Fig. 5, which is adapted to be xedly mounted on a floor ,3l (Fig. 1) which forms a closure beneath the skirt. This casting comprises `a central rcore 32 and `.a lower piece 33 which project yhoriaontally from a connecting member 311. The latter is shaped like a fragment of frustuin of a cone and is so arranged thatat its upper end it partly surrounds but does not touch the downwardly projecting sleeve 35 of the table 12 which is keyed to the shaft 11. An upper plate 36, as shown in Fig. 6, is removably fastened to this castingSO and is so shaped and arranged that it will lie closely beneath the under surface of the :table 12. The casting and the plate 36 are made of iron andthe table itsel-fis made of iron so tha-tthey will all .conduct the magnetic flux. The table 12 fand the plate 36 constitute the upper return path for the flux and the lower part 33 provides a second path. An electro-magnetic winding, as shown in Fig. 7, is suitably fashioned to surround the central core 32 and electric current is conducted to this winding by suitable means, not shown, so as to cause the outer end of the core 32 to form one pole of a magnet and the parts 33, 34 and 36 with the table 12 to form a divided return circuit for the magnetic lines of force.

The skirt 2O serves as a revolving pole piece for the magnet and it is preferably made as illustrated of two dissimilar'materials one of which is magnetic and the other non-magnetic so as to form a strong field where required. To this end the skirt is formed with a central annular portion 40 of iron which lies closely adjacent the outer end of the core 32 and substantially in line with the axis thereof. Between this ring 40 and the table 12 above and the lower edge 41 of the skirt are two portions ofnon-magnetic material 42 and 43 which may be made of brass or other suitable metal. If desired the skirt may be made of an iron casting having inserts of non-magnetic metal, such as babbitt, supported between ribs arranged in reticulated fashion. It will therefore be seen that the lines of force, indicated diagrammatically in Fig. 4, by the lines 45, will traverse the iron parts which form the magnetic circuit and some will jump through the air over the non-magnetic spacing blocks 42 and 43 so that they will lie within the path of the material descending over the skirt. In order to concentrate and localize the lines of flux, the parts 40, 41 and the depending edge of the table may be made beveled, as shown in Fig. 4, so as to overlap the inserts 42 and 43. The only other air gaps in the circuit are those where the lines of force must jump from the ring 40 to the core 32 and from the ring 41 to the part 33 and from the plate 36 to the table part 12. The plate 36 forms a path of great area and low reluctance opposite the table top whereby the flux may pass easily to the table. This plate serves also to hold the winding in place on the core.

The core 32, as shown in dotted outlines in Fig. 3, lies beneath the feeding opening leading from the scraping knife 18`to the chute 22, and it extends laterally beneath the skirt nearly to the scraper 27, thus providing a magnetic held beneath the stream and far enough to one side thereof to insure positive separation of the magnetizable material. When the tramp iron gets beyond the influence of the magnet it will fall 0E the table skirt, but if residual magnetism tends to hold it on the table the scraper will remove it and cause it to fall down the inclined shelf into the opening 25. This insures that all material passing through the machine will come under the influence of the magnet and that the tramp iron will be positively separated therefrom and deposited in a pile by itself.

In order to regulate the amount of material fed by means of the scraper knife 18, this part is preferably mounted so as to move in and out towards the center of the hopper. This may be accomplished as illustrated particularly in Fig. 3 by mounting the knife 18 on a sleeve 6() which is threaded onto the screw 61 mounted in suitable bearings in the casing and adapted to be turned by the hand wheel 62. The scraper 18 has a tapering shape (Fig. 1) with the wedge forward and it is so located that it presents a face to the revolving material within the hopper which makes an acute angle to the direction of travel of the material as indicated by the arrow in Fig. 3. The scraper is moreover so mounted that it will move parallel with itself and make the same angle with the line of travel of the material for all positions of adjustment. This makes it possible to regulate the feed easily and accurately. In order to prevent material which rides up over the scraper from going through or jamming in the opening in the rear of the scraper, a slide 44 is arranged to close this back opening. The slide is movably held aga-inst the lower outer portion of the hopper by the head of a cap screw 39 on the hopper projecting through the slot 46 in the slide. The latter is moved with the scraper by means of a link 47 connecting with the sleeve 60, so that as the knife 18 moves in and out the slide 44 will serve to close the j opening back of the knife. The coal may be suitably agitated and caused to revolve in the hopper by means of a plate 48 and a rod 49 xed on an extension 50 screwed to the shaft The table 12 may be rotated at various shaft 54. The worm on the shaft 54 meshes i with a worm gear 56 which is suitably fixed on the shaft 11. The clutch shaft"i53 carries two sprockets, one of which is to be connected by a slidable clutch of usual construct-ion to l the shaft, and these are connected by chains with the large and small sprockets 58 and 59 on the worm shaft, all of which will be well understood by one skilled in the art.

It will be understood that this device is of n `general utility for feeding various types of material and separating iron therefrom. The operation will be obvious from the above disclosure. As the material revolves in the hopper, some of it is caught by the scraper 18 and yforced over the edge of the annular portion 17 of the table l2. As it slides down the skirt to the mouth 22 of the chute 23, it passes over the pole pieces of the magnet and is subjected to a strong field. The tramp iron Y is caught and held by the iron portions of the skirt until they pass under .the scraper 27., whereupon the iron is removed and caused to fall ,do-wn the chute 25 and so be removed from the device.

Having-thus described our invention, what We claim as new and desire to secure by Letters Patent is: Y

l. AA magnetic separator Acomprising a fr-ustofeonical table rotatable about a vertical axis, means for delivering'a localized stream ofrmaterial onto the table, Ya pole piece and a strip of non-magnetic material associated therewith which extend peripherally around .the table, said pole piece and non-magnetic strip having inclined outer faces coincident with the conical outer wall of the table, a stationary magnet wholly beneath the table, .One end of the core of the magnet being close to said pole piece and adjacent to the stream of material, and iron parts forming la return path to the other end of the core for the flux traversing the non-.magnetic strip, and means for removing ,magnetized material from the table- 2. A magnetic separator comprising a table having a depending frusto-conical skirt ro- .tatable about a vertical axis, means to feed a localized stream of material over the` outer surface of the Skirt, saidV ,Skirt having conti-I1- uous pole pieces separated by non-magnetic materia-l which extend around `the peripheral surface thereof and forma portion of said conical surface, a stationary magnet loca-ted wholly beneath the table and havingits core .close to one of said pole pieces, means form-ing a return path for the flux, and means to re move the magnetized material from the skirt.

3. yA magnetic separator comprising va table having a depending flared skirtV which is rotatable abouta Vertical axis, means to feed .a localized stream of material .over the skirt, the outer surface of said -skirt having iron .pole pieces extending about its periphery which are separated vertically by non-mag netic material, an electromagnet 'beneath the table having a substantially horizontal iron core and 'an iron portion forming a return path for the flux which are located close to said pole pieces, and means to remove the magnetized material from the table.

4. A magnetic separator comprising a depending frusto-conical table rotatable about a vertical axis, means to feed a localized stream o-f material thereover, spaced iron pole pieces extending through the skirt, nonmagnetic material between the pole pieces von the outer surface of the skirt, a stationary electromagnet wholly beneath the table and having a horizontal core and iron parts providing a localized field of flux .close to each pole piece beneath said stream, said iron parts being connected with the core and forming a return path for the flux, and means for removing'magnet-izable material from the table.

5. A magnetic separator comprising a flat table having a Adepending skirt which is rotatable about a vertical axis, the outer surface of said skirt having coincident therewith three pole pieces separated by non-magnetic lmaterial which extend about its periphery, and a stationary electro-magnet Wholly beneath the skirt having three spaced iron portions, the central one of which is the magnet core and the others forming return pathsfor the flux, said iron portions being located close to the pole pieces in the table and forming a localized eld of flux therein. f

Signed at Worcester, Massachusetts, this 25th day of March, 1926. y

ROBERT SANFQRD RILEY. HAROLD F. WALTON.

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